1. Field of the Invention
The present invention relates to a method for testing a mold structure, a mold structure, a mold original master and a magnetic recording medium, and particularly relates to a method for testing a disc-shaped mold structure having a convexo-concave pattern formed on a surface thereof based on a desired design pattern, a mold structure tested by the test method, a mold original master tested by the test method, a magnetic recording medium produced by using a mold structure tested by the test method and a magnetic recording medium produced by using a mold original master tested by the test method.
2. Description of the Related Art
In the field of magnetic recording media, generally, with an increased amount of information, a medium is desired which is capable of recording a large amount of information (having high capacity) and costs less and preferably allows for a so-called high-speed access so that a necessary part of the medium can be read in a short time. As an example of such a magnetic recording medium, a high density magnetic recording medium (magnetic disc medium) used in hard disc devices or flexible disc devices has been known.
A convexo-concave pattern formed in a surface of a high density magnetic recording medium (magnetic disc medium) is formed according to a convexo-concave pattern formed in the surface of a mold structure. However, after the high-density magnetic recording medium (magnetic disc medium) is incorporated into a disc drive, it sometimes turns out that there is a defect originating from the convexo-concave pattern formed in the surface of the high-density magnetic recording medium, which causes a delay in the feedback.
To solve such a problem, a method is conceivable in which after testing the quality of a convexo-concave pattern formed on a surface of a mold structure, the convexo-concave pattern is formed in the surface of the high density magnetic recording medium (magnetic disc medium) using the mold structure that has passed the test.
As the method of testing a convexo-concave pattern formed in the mold structure, there are for example, the following method: a method to measure the length of a top surface using a measuring scanning electron microscope, a method to measure the height of a pattern in the cross sectional direction using a transmission electron microscope (TEM), and a method to evaluate a pattern cross section using a critical dimension atomic force microscope (CD-AFM) and an atomic force microscope (AFM). These test methods, however, are suitable for testing a part of a convexo-concave pattern, and it is very difficult to test a convexo-concave pattern formed on the entire surface of the mold structure.
Furthermore, many conventional HDD inspection systems are using laser light, and while they can detect defects on a supper smooth surface, they cannot detect defects of a mold structure with a convexo-concave pattern formed on its surface, because laser light is scattered in the convexo-concave pattern. Alternatively there is a method to recognize a convexo-concave pattern by deep UV method as a semiconductor test method, however, it is very difficult to test a convexo-concave pattern formed on the entire surface of the mold structure by this method and the resolution is low (at a level of 100 nm).
Note that a method for testing a convexo-concave pattern using a magnetic transfer method is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2004-253040, however, this test method was limited to methods of testing a master carriers for magnetic transfer. In addition, a convexo-concave pattern corresponding to data areas (discrete area) is different from a convexo-concave pattern corresponding to servo areas in height. As a result, the convexo-concave pattern corresponding to the data areas (discrete area) and the convexo-concave pattern corresponding to the servo areas cannot be magnetically transferred by an in-plane magnetic recording method at a time.